Apparatus and method for cutting and breaking rock

ABSTRACT

A continuous mining machine for excavating an in-place mass of rock or other material having echeloned concentric cutter heads that remove rock or other material from annular concentric grooves, leaving bands of undisturbed material between the grooves cantilevered from the in-place mass, and a breaking device carried by the machine adjacent and behind the cutter head for breaking the undisturbed bands from the mass with an intermittent or continuous breaking force.

United States Patent [191 Patrick June 3,1975

[ APPARATUS AND METHOD FOR CUTTING AND BREAKING ROCK [75] Inventor: James G. Patrick, Hillsborough,

Calif.

{73] Assignee: Bechtel International Corporation,

San Francisco, Calif.

[22] Filed: June 15, 1973 [21] Appl. No.: 370,388

[52] US. Cl. 299/10; 175/57; 175/250;

[51] Int. Cl E2lb 9/18; 1321c 41/00 [58] Field of Search 299/10, 18, 86, 90; 175/404, 332, 333, 57, 250

[56] Reierences Cited UNITED STATES PATENTS Schmidt 299/86 X 1,723,330 8/1929 Cross et a1. 175/333 X 3,050,292 8/1962 Newton et a1. 299/86 3,288,532 11/1966 Carver 299/86 X Primary ExaminerErnest R. Purser [57] ABSTRACT A continuous mining machine for excavating an inplace mass of rock or other material having echeloned concentric cutter heads that remove rock or other material from annular concentric grooves, leaving bands of undisturbed material between the grooves cantilevered from the in-place mass, and a breaking device carried by the machine adjacent and behind the cutter head for breaking the undisturbed bands from the mass with an intermittent 'or continuous breaking force.

8 Claims, 12 Drawing Figures FIB-JD- FIE--11 APPARATUS AND METHOD FOR CUTTING AND BREAKING ROCK BACKGROUND OF THE INVENTION Utilities located in the flat central area of the United States do not have available economic sites for conventional pumped storage and. therefore. are seriously considering underground pumped storage. Also, because of environmental objections. other utilities are actively investigating underground pumped storage even though conventional hill and valley sites are available. The key to economic underground pumped stor age is the cost of excavating the underground cavity. The present invention provides a device for rapidly excavating a suitable cavity in rock at low cost.

Other applications of the invention include all types of tunne s such as those for railroads, highways, water and other utilities, as well as all forms of underground excavations such as in the mining industry.

The demand for larger diameter and longer tunnels has challenged the engineering and construction industry to devise less costly methods for driving tunnels. One answer to this challenge has been the development of the mechanical mole. These machines are setting new records in driving rates. Furthermore, because they produce a smooth bore with no shattering of the surrounding rock, other costs such as tunnel supports are reduced. Mechanical moles have operated in many types of rock. Among the many factors influencing the economics of mechanical moles are the rate of forward progress achieved and the effectiveness of the cutters. Present mechanical mole machines operate on the principle of cutting or cutting and chipping small pieces of rock from the full area at the face of the tunnel being excavated. As the rock being excavated becomes harder, more energy is required, forward progress decreases and the additional wear on the cutters per unit of advance increases cost.

SUMMARY OF THE INVENTION Unlike the mechanical moles now in operation, the method or principle of my invention is to out only a small percentage 35%) of the full area at the face of the tunnel being excavated in the in-place mass of rock or other material and to remove the remainder by intermittently breaking from the rock mass pieces of rock which will vary in size but could be one cubic foot in volume or larger. The concept is based on providing narrow concentric cutter heads which by cutting action remove the rock from annular concentric grooves leaving bands of undisturbed rock between the removed concentric grooves. The bands of undisturbed rock are broken from the inplace mass by a breaking force acting in a radial direction or one otherwise transverse to the direction of excavation. The broken pieces of rock will be of various size depending upon the strength and natural jointing structure of the rock being excavated. As the amount of rock to be removed by cutting (or cutting and chipping) action represents only a small percentage of the full area at the face of the tunnel, less energy will be consumed by the cutting as compared to mechanical moles now in operation. Conversely, forward progress will increase substantially.

The breaking force may be provided, for example, by hydraulically operated cylinders mounted within the concentric cutter heads, or, alternatively, by fixed wheels. By utilizing leverage, a large breaking force breaks pieces of rock off the concentric bands of inplace rock, which are cantilevered from the in-place rock mass.

The reaction to the breaking force is carried by the solid mass of in-place rock. This is accomplished by echeloning the concentric cutter heads, which cut the concentric grooves, for example, such that the outer cutter heads are forward of the adjacent inner cutter heads. This arrangement of concentric bands of undisturbed rock cantilevered from the in-place rock mass and echeloned. such that the outer bands are forward of the adjacent inner in-place bands, allows the breaking means, for instance. to consist of two close coupled wheels actuated by a hydraulic cylinder through a lever arm. An outward breaking force is provided by a narrow wheel having a rounded surface such that a concentrated force can be exerted. An inward reaction force is carried by a wider wheel having a flat surface such that the reaction force is distributed to the solid mass of the inner in-place rock. As the major portion of the rock breaking force (as well as the reaction force) is applied to in-place rock, the stress within the cutter head assembly is minimized. Also, the contacts between the rock and the two wheels are rolling contacts absorbing minimum energy. The rock breaking force is applied intermittently on the several bands of rock at approximate intervals of one foot of forward progress without interruption of the cutting process. The broken rock falls between the arms of the cutter support wheel to the floor of the tunnel for removal.

An alternative fixed beveled wheel breaking device operates on the same principle, but the breaking action is continuous and not intermittent.

The principal object of the invention is to provide a mechanical excavating device for rapidly excavating an in-place mass of rock or other material at low cost and with a minimum expenditure of energy.

Other objects and advantages will become apparent upon consideration of the following description of a specific embodiment of the invention and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view ofa mechanical mole utilizing my invention ready for operation in a tunnel;

FIG. 2 is a rear view of the device shown in FIG. 1;

FIG. 3 is a side elevation partly in section through the device shown in FIG. 1;

FIG. 3A is a side elevation partly in section through a modified form of the device;

FIG. 4 is a section taken through one of the cutting parts of the device showing the cutter in position in relation to one form of breaking and reaction wheels;

FIG. 5 is a section taken along the line 5-5 in FIG.

FIG. 6 is a section taken along the line 6-6 in FIG.

FIG. 7 is a section taken along the line 7-7 in FIG.

FIG. 8 is a section taken along the line 8-8 in FIG.

FIG. 9 is a side elevation showing the assembled alternative beveled wheel breaking means;

FIG. 10 is a section taken along the line I0-10 in FIG. 9; and

FIG. 11 is a section taken along the line llll in FIG. 9.

DESCRIPTION OF THE PREFERRED EMBODIMENT As appears in FIG. 1, 2 and 3, one specific embodiment of a mechanical mole utilizing my invention comprises a cutter head assembly including a series of concentric annular cutter heads 5, 6, 7. 8 and 9 which are supported by spaced arms 11 extending radially from a central drive shaft 12 which is suitably rotated by means not shown. The annular cutter heads are echeloned forwardly from the center as appears in FIGS. 1 and 3. Extending forwardly from each of the cutter heads through 9 are a plurality of individual cutters, generally indicated at 14. The type, size and number of cutters depend on several variables including the type and hardness of rock or other material to be excavated, the diameter of the tunnel and the distance of the cutters from the tunnel centerline. The cutters are operated by the rotation of the cutter head assembly and are positioned on the concentric annular cutter heads such that the width of the circular groove cut by each individual cutter exceeds the thickness of the cutter head.

The resulting space between the cutter heads and the undisturbed concentric bands of rock prevents loss of energy by friction between these in-place bands of rock and the cutter heads. Furthermore, these spaces permit outward movement of the rock when pressure is exerted by the described breaking means to break pieces of rock from the concentric bands which are cantilevered from the undisturbed mass of rock.

One breaking means shown in FIGS. 4-8 includes an assembly of rounded roller or breaking wheel 22 mounted upon a shaft 26 guided in opposite upright slotted supports 27 mounted within the concentric annular cutter heads. The upright supports 27 are slotted as at 28 to permit the breaking wheel to move radially with respect to the center of the cutter head. Shaft 26 is carried on lever 29 which may be pivoted to move the breaking wheel toward the outboard concentric band of undisturbed rock. Flat wheel 21 is mounted upon a shaft 31 carried at the forward end of lever 29. The opposite end 32 of lever 29 engages a rod 33 which extends from a piston (not shown) that is provided in hydraulic cylinder 34. Intermittent extention of piston rod 33 radially outwardly moves breaking wheel against the outboard cantilevered band of undisturbed rock with a substantial breaking force. As is shown in FIGS. 4-8, the reaction of the breaking force is transmitted to solid in-place rock by flat roller 21 (FIG. 8). The face of breaking wheel 22 (FIG. 7) is rounded to exert a concentrated breaking force while the face of the reaction wheel 21 is flat to distribute the reaction force over a broad area of solid rock.

The thickness of the cutter heads need be only sufficient to contain the breaking mechanisms. The controlling dimension is the travel of the piston in the hydraulic cylinder 34. This travel is a function of the size of the hydraulic cylinder, operating pressure of the hydraulic cylinder and the leverage required to produce sufficient force to break the particular rock in the concentric bands.

An alternative breaking mechanism is shown in FIGS. 9, l0 and 11. This alternative includes a beveled or coneshaped breaking wheel 41 which continuously breaks rock from the cantilevered concentric bands of rock as the mole advances. The beveled breaking wheel 41 mounts on a shaft 42 which is carried intermediate the ends of opposite lever arms 43 and is guided in opposite slots 44 provided in upright supports 46. A flat roller or wheel is rotatably mounted at each end of lever arms 43 on a shaft 48 to distribute the reaction force to the inboard in-place rock.

The thickness of the concentric bands of rock which are to be removed by breaking can vary with the strength of the rock being excavated and the natural jointing system. Also, the thickness of the outer bands of rock (or space between cutter heads) can be greater than those toward the center because rock should break easier when on a large radius curve than a small radius curve.

The cutter heads are echeloned apart a distance such that the reaction wheel has firm bearing on in-place rock and the breaking wheel exerts breaking force on a band of rock remote from where it is cantilevered from the in-place mass. The amount of cantilever and therefore the amount of echeloning between concentric bands is again a function of rock characteristics and can vary with rock type and design features of the mole.

As the rock is broken from the concentric bands it will rotate with the cutter head assembly and then fall to the floor of the tunnel behind it primarily at the sides of the tunnel during the upward and downward motion of the broken rock while rotating with the assembly. The advance of the cutter heads and the intermittent breaking of additional rock also will displace the broken rock to the rear where it falls between radial arms 11 to the floor of the tunnel. As the cutting head assembly is generally coneshaped, rock will be deposited over a length of the tunnel floor. In some instances it may be desireable to add guide vanes on the concentric cutter heads to provide a more positive means of displacing the broken rock to the rear. This provision requires a wider cut by the cutters and may not always be neces sary.

While the principal purpose of the invention is to provide a mechanical mole which will economically drive tunnels in hard rock, it also should reduce the cost of driving tunnels by mechanical moles in all types of in-place rock and other materials. Optimum economy is attained in a specific rock or other material by modification of the several variables available including type and number of cutters, thickness of cutter heads, spacing between the concentric cutter heads, length of cutter heads and amount of echeloning between cutter heads.

I claim:

1. A continuous mining machine for excavating an in-place mass of rock or other solid material comprising a plurality of concentric annular cutter heads spaced apart and echeloned in the direction of excavation; means for rotating said cutter heads;

at least one cutter mounted on each cutter head for cutting an annular groove in said mass as the cutter heads advance; and

breaking means for applying breaking force to undisturbed bands of material between said grooves cantilevered from said in-place mass, said breaking means being mounted behind said cutters and including a breaking wheel supported within the an nular cutter head and extendible radially from the annular cutter head to apply a breaking force to the adjacent band of undisturbed material, and reaction means operatively connected with the breaking wheel to distribute the breaking force reaction from the breaking wheel to the in-place mass.

2. A device as in claim 1, wherein said machine includes a drive shaft; said plurality of concentric annular cutter heads mounted on spaced arms extending from said drive shaft; means connected with the drive shaft for rotating the drive shaft; each of said annular cutter heads extending forwardly of the drive shaft a greater distance than the next adjacent inner cutter head.

3. A device as in claim 1 wherein each breaking wheel is pivotally mounted upon a lever, and said reaction means includes at least one reaction wheel carried by the lever to distribute the breaking wheel reaction to said breaking force to said in-place mass.

4. A device as in claim 3 wherein a hydraulic cylinder is operatively connected to the levers to intermittently pivot each lever to move an associated breaking wheel into engagement with said band and said reaction wheel into engagement with said in-place mass.

5. A device as in claim 3 wherein said breaking wheel is a beveled whee] continuously extending radially from said cutter head.

6. A method for excavating an in-place mass of rock or other material, using a machine including a plurality of concentric annular cutter heads each having a cutter mounted thereon and a breaking means carried by the cutter heads behind the cutters and a reaction means carried by the cutter heads in operative connection with the breaking means, comprising the steps of operating the machine to cut a plurality of concentric annular grooves in the mass of rock echeloned in the direction of excavation and spaced apart by bands of undisturbed material cantilevered from the in-place mass, engaging said bands of undisturbed material with the breaking means and applying a breaking force to the bands in a direction transverse to the direction of excavation, and simultaneously engaging the in-place mass with the reaction means and distributing the reaction to the breaking force to the in-place mass.

7. A machine implemented method for excavating an in-place mass of rock or other material comprising the steps of first cutting a plurality of concentric annular grooves in said mass, said annular grooves being echeloned in the direction of excavation, with adjacent grooves being spaced apart by bands of undisturbed material cantilevered from said in-place mass and a root end attached to the in-place mass; and

then applying a breaking force to each of said cantilevered bands of undisturbed material adjacent the free end thereof in a direction transverse to that of excavation and simultaneously distributing the reaction to said breaking force to an adjacent noncantilevered portion of said in-place mass at a location forward of the root end of each respective cantilevered band of undisturbed material, each said breaking force and the distributed reaction thereto being applied to opposite sides of a respective groove.

8. A method for excavating an in-place mass of rock or other material comprising the steps of first cutting a plurality of concentric annular grooves in said mass,

said annular grooves being echeloned in the direction of excavation, with adjacent grooves being spaced apart by bands of undisturbed material cantilevered from said in-place mass, and

then applying a breaking force to each of said cantilevered bands of undisturbed material in a direction transverse to that of excavation and simulta neously distributing the reaction to said breaking force to an adjacent non-cantilevered portion of said in-place mass, each said breaking force and the distributed reaction thereto being applied to opposite sides of a respective groove. 

1. A continuous mining machine for excavating an in-place mass of rock or other solid material comprising a plurality of concentric annular cutter heads spaced apart and echeloned in the direction of excavation; means for rotating said cutter heads; at least one cutter mounted on each cutter head for cutting an annular groove in said mass as the cutter heads advance; and breaking means for applying breaking force to undisturbed bands of material between said grooves cantilevered from said inplace mass, said breaking means being mounted behind said cutters and including a breaking wheel supported within the annular cutter head and extendible radially from the annular cutter head to apply a breaking force to the adjacent band of undisturbed material, and reaction means operatively connected with the breaking wheel to distribute the breaking force reaction from the breaking wheel to the in-place mass.
 1. A continuous mining machine for excavating an in-place mass of rock or other solid material comprising a plurality of concentric annular cutter heads spaced apart and echeloned in the direction of excavation; means for rotating said cutter heads; at least one cutter mounted on each cutter head for cutting an annular groove in said mass as the cutter heads advance; and breaking means for applying breaking force to undisturbed bands of material between said grooves cantilevered from said in-place mass, said breaking means being mounted behind said cutters and including a breaking wheel supported within the annular cutter head and extendible radially from the annular cutter head to apply a breaking force to the adjacent band of undisturbed material, and reaction means operatively connected with the breaking wheel to distribute the breaking force reaction from the breaking wheel to the in-place mass.
 2. A device as in claim 1, wherein said machine includes a drive shaft; said plurality of concentric annular cutter heads mounted on spaced arms extending from said drive shaft; means connected with the drive shaft for rotating the drive shaft; each of said annular cutter heads extending forwardly of the drive shaft a greater distance than the next adjacent inner cutter head.
 3. A device as in claim 1 wherein each breaking wheel is pivotally mounted upon a lever, and said reaction means includes at least one reaction wheel carried by the lever to distribute the breaking wheel reaction to said breaking force to said in-place mass.
 4. A device as in claim 3 wherein a hydraulic cylinder is operatively connected to the levers to intermittently pivot each lever to move an associated breaking wheel into engagement with said band and said reaction wheel into engagement with said in-place mass.
 5. A device as in claim 3 wherein said breaking wheel is a beveled wheel continuously extending radially from said cutter head.
 6. A method for excavating an in-place mass of rock or other material, using a machine including a plurality of concentric annular cutter heads each having a cutter mounted thereon and a breaking means carried by the cutter heads behind the cutters and a reaction means carried by the cutter heads in operative connection with the breaking means, comprising the steps of operating the machine to cut a plurality of concentric annular grooves in the mass of rock echeloned in the direction of excavation and spaced apart by bands of undisturbed material cantilevered from the in-place mass, engaging said bands of undisturbed materiAl with the breaking means and applying a breaking force to the bands in a direction transverse to the direction of excavation, and simultaneously engaging the in-place mass with the reaction means and distributing the reaction to the breaking force to the in-place mass.
 7. A machine implemented method for excavating an in-place mass of rock or other material comprising the steps of first cutting a plurality of concentric annular grooves in said mass, said annular grooves being echeloned in the direction of excavation, with adjacent grooves being spaced apart by bands of undisturbed material cantilevered from said in-place mass and a root end attached to the in-place mass; and then applying a breaking force to each of said cantilevered bands of undisturbed material adjacent the free end thereof in a direction transverse to that of excavation and simultaneously distributing the reaction to said breaking force to an adjacent non-cantilevered portion of said in-place mass at a location forward of the root end of each respective cantilevered band of undisturbed material, each said breaking force and the distributed reaction thereto being applied to opposite sides of a respective groove. 